apache already installed. I want to install php

I already have linux/apache running on a webserver and I am succesfully hosting pages and serving them to the internet. I have now run an installation procedure for PHP. I am required to now run some ./configure commands. I am inexperienced with Linux. Is a ./configure command recompiling apache or php, or just altering some settings. Will my webserver still serve the pages it currently serves after I run a ./configure apachectl type of command?

each package you download for linux will most likely have a configure, so there is one for apache and php--you simply go to their source directories to run the one you want.

there are 3 basic things you run on a linux machine:

./configure this is ran first with the options you would like compiled in, it also checks many things on your machine to make sure it will work ok.

make make builds off of configure...

make install this is what truly puts the files in place.

you web server should remain the same, page-serving-wise, if you reconfigure. it should not overwrite your configuration files if they already exist; for safety measures you can always make a backup copy.